The use of natural light-conducting tubes, which allow capturing sunlight through a skylight and conducting it through the interior of the tubes, coated with a highly reflecting material to that effect, in order to be delivered to different interior lighting points, is known for lighting up the interior space of homes, offices and the like. It is thus possible to light up interior rooms using sunlight, with the consequent energy saving, since the generation of light using electric current is not necessary. Since the sun changes its position throughout the day, the light capturing skylight can be adapted by means of its orientation and the placement of optical lenses to optimize the capture of sunlight between dawn and twilight. Lighting up interior spaces during the hours in which there is sun is thus solved. Nevertheless, the light level may not be constant due to the passage of clouds or to the fact that the day is not sunny enough, and therefore the amount of captured light may not be enough for lighting up the interior rooms. Likewise, lighting up interior rooms during the night is not possible. To solve this drawback, the introduction of lighting elements in the light capturing tube has been suggested, such that in situations of insufficient lighting by the captured sunlight, this lack of light can be made up for by means of the use of incandescent lights such as bulbs or fluorescent lamps. Nevertheless, the use of this type of bulb results in a low efficiency of the energy use, since most of the energy is dissipated in the form of heat. Another drawback of this type of bulb is the space it occupies inside the natural light-conducting tube, preventing the passage of sunlight and therefore reducing the light level of the interior rooms during the hours of sun, in which the use of artificial lighting means is not necessary. Furthermore, the lifetime of the aforementioned light sources is limited, therefore when they burn out at the end of their service life they must be replaced with the consequent cost. Since this type of lamp is normally installed in ceilings and protected by means of diffuser lenses or glass, the bulb changing operation is furthermore difficult.
The use of high-power light-emitting diodes (LEDs) for lighting is also known, since it has advantages in terms of their energy efficiency and in terms of their consumption, which is considerably lower than that of known bulbs, in addition to having a much longer service life, up to the point in which their replacement during the service life of the lamp is not necessary. Nevertheless, high-power LEDs are highly sensitive to overheating and require working at relatively low temperatures. In the case of operating at a too high temperature, their service life time decreases drastically, being able to burn out immediately in high temperature situations. This means that their use inside natural light tubes is not possible because in order to maintain a good insulation between the interior and the exterior, natural light tubes are sealed and do not allow air exchange. Therefore, the heat dissipation level cannot be enough for the good operation of the LEDs.
The fact that LEDs work at the correct temperature is indispensable to assure their correct operation and prevent them from burning out, since high-power LEDs are usually welded to the lamp and their replacement is virtually impossible, the entire lamp having to be replaced or the intervention of a specialized technical service being required.